Rokinon 800mm f/8 Manual Focus
Telephoto Mirror Lens
The most powerful Rokinon mirror lens yet, at 800mm, this lens is incredibly powerful for your wildlife, nature and sports photography. It includes lens caps, lens case, and 1 year Rokinon warranty.
T-Mounts are available for all the digital SLR systems, as well as for C-mount systems or for nearly any film camera. However, in every case the fixed f/8.0 aperture is not communicated to the camera body. As such, you can use the camera in the "M" manual exposure mode or the "A" aperture-priority mode (if your camera is so equipped).
This lens, at 4.4 x 5.2" and just over 2 pounds, has a broad diameter and stocky build. It is a bit easier to handle than a normal 800mm refractor lens, but it is still a super-telephoto in any case (you should use a tripod/monopod in any case for best results). It also has a much different rendering of out of focus areas than a normal lens; highlights will be doughnut-shaped rings with more saturation and contrast on the edge of the ring than on the center.
Catadioptric lenses have several drawbacks. The fact that they have a central obstruction means they cannot use an adjustable diaphragm to control light transmission. This means the lens's aperture value is fixed to the overall focal ratio of the optical system (typically f/8 for 500 mm designs, or f/11). Their modulation transfer function shows low contrast at low spatial frequencies. The folded optical path does reduce the length of the lens, but increases its width.
Their most salient characteristic is the annular shape of defocused areas of the image, giving a doughnut-shaped 'iris blur' or bokeh, caused by the shape of the entrance pupil.
Several companies made catadioptric lenses throughout the later part of the 20th century. Nikon (under the Mirror-Nikkor and later Reflex-Nikkor names) and Canon both offered several designs, such as 500 mm 1:8 and 1000 mm 1:11. Smaller companies such as Tamron also offered their own versions. Of the major manufacturers, currently only Sony (formerly Minolta) offers a 500 mm catadioptric
lens for their Alpha range of cameras.
Samyang offers a variety of uniquely priced optics, delivering a lot of optical
capability for very little money. These rebranded catadioptric lenses are
available under the names of Bower, Opteka,
Phoenix, Rokinon, Sakar,
Vivitar and others.
Mirror lenses can produce pictures and under carefully chosen conditions they
may even produce pretty good ones. However, these situations are rare and therefore
most will have unsteady background blur. Most mirror lenses suffer from a rather mediocre optical performance. This may all be fine for personal purposes and for documentation but most likely you'll not be able to sell such pictures. Therefore a classic (refractive) lens like a 400/5.6 fix-focal or even a xx-500mm zoom
or even a 70-300-f/4-5.6 with a 1.4 or 2x teleconverter is usually a better and more serious approach. Nonetheless mirrors are quite cheap
(but you get what you pay for).
(To rephrase the paragraph above: Mirror lenses are Junk!)
This lens is an ideal candidate for astrophotography use when mounted to a Vixen GP2 Photo Guider (or other motorized equatorial telescope mount).
• Fixed-aperture 800mm f/8.0 mirror lens in T-mount
• Multicoated optics
• Distinct out-of-focus highlight characterization
• White lens barrel helps prevent heat retention
• Accepts small, less-costly 30.5mm filters upon rear of barrel (also accepts 105mm filters)
• Made in South Korea
• Rokinon 800mm Mirror Lens
• Front & Rear Lens Caps
• Lens Case
• 1-Year Warranty
Better than I expected
By Jeff from Ithaca on 3/3/2010
The lens has a much sharper focus than I expected and I've even been able to get some nice wildlife shots with it. Obviously there is no controlling the aperture with this lens, so make sure you want a F/8.
Not impressed at all
By Constantine from Cyprus on 2/10/2010
To begin with, I didn't expect a lot from a catadioptric 800mm lens at this price range. I don't usually shoot this kind of photo and I was looking for an occasional compact alternative to the 80-400mm with the teleconverter.
This lens is extremely soft. Comparing it to the 80-400mm at 400mm with a 2x teleconverter it's considerably softer. I find that its quality is about the same as a crop of a refractive lens at 400mm (that is resizing 2x an image made with a 400mm lens) and even worse.
To make things worse there is no tripod collar on the lens and even with a pro body the center of weight of the system is somewhere on the lens, thus becoming really unstable on a tripod.
I would pick any of the superzooms instead of this lens any day and either crop and resize or use a teleconverter.